


It Started With A Crash

by LumianaKatenke



Category: Gravity Falls
Genre: Alien Biology, Alien Cultural Differences, Alien Culture, Alien Sex, Anal Sex, Bill is Essentially an Alien Wolf, Essentially this is, Eventual Smut, Eventual mpreg, Hermaphroditic Bill Cipher, I Wrote More Than 7000 Words in 2 Days, I Wrote This Instead of Sleeping, Intentional Voyeurism, Interspecies Relationship(s), M/M, Masturbation, Mpreg, Original au, Other, Oviposition, Porn With Plot, Shapeshifting, Unintentional Exhibition, Unique Dick Idea, mini-series, sorta - Freeform, this was supposed to be a oneshot
Language: English
Status: In-Progress
Published: 2020-08-09
Updated: 2021-02-08
Packaged: 2021-03-05 21:14:43
Rating: Mature
Warnings: No Archive Warnings Apply
Chapters: 3
Words: 14,786
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/25801951
Author URL: https://archiveofourown.org/users/LumianaKatenke/pseuds/LumianaKatenke
Summary: When an alien craft falls from the sky, Dipper finds himself taking in a strange wolf-creature that he quickly forms a close bond with. One that is far closer than he had ever expected when he went on that walk.___________This fic was meant to just be a oneshot pornfic but it got out of hand. If you are not ok with mpreg, do NOT read.
Relationships: Bill Cipher/Dipper Pines
Comments: 41
Kudos: 143





	1. Chapter 1

**Author's Note:**

> Seriously this fic may start off slow but the kinks are still here. I initially just wanted to write some kinky weird-ass combo of (sentient and consensual) wolf sex mixed with oviposition, but as I wrote, it kept getting longer so here we are. Basically think of this as a very long oneshot that had to be broken down into chapters so it was more easily consumed by you, the readers. I had written just over 15 pages when I realized that I should probably break it down. Now at just over 19 pages, I got the urge to start posting the "chapters".
> 
> And yes I am still working on the other fics, things have been hectic lately so I kind of poured myself into this for the time being since it's less stressful to keep track of all of the details.
> 
> I hope you enjoy.
> 
> -Lumi

A loud crash echoes throughout the forest surrounding the town of Gravity Falls, tremors from the impact reaching even those who slept in town, though they remained undisturbed in their slumber. That is, all except a young man who had been out for a late night hike. Dipper Pines had had trouble sleeping, so he decided to go on a short hike into the woods to a clearing, intending on stargazing.

However, as he had reached the clearing, a burning streak of something flashed by above him, causing him to duck and cover his head. Moments later, it crashed to the ground hard enough to knock him on his ass, sending his flashlight skittering away into the undergrowth.

He cursed softly, climbing to his feet and brushing off the grass and dirt from his ass as he walked over to the flashlight, picking it up before looking around for the direction where the... whatever it was, had landed. The brunette spotted a column of smoke beginning to rise in the distance along with the faintest glow of fire. He frowned and jogged towards it, wondering what the hell had fallen out of the sky.

It took him a mere 5 minutes to reach the crash site, having to carefully pick his way through broken trees and scattered branches before pausing at the lip of the deep gauge in the ground left behind by the... He looked over, following the ruined earth to the source. At the far end was a silvery red spacecraft that had some kind of alien symbols painted on the side.

Dipper let out an excited gasp as he realized that it was a UFO, stepping over the lip and sliding down into the furrow, narrowly avoiding twisting his ankles multiple times in his eagerness. Once at the bottom, he dashed forward, dodging around burning pieces of debris until he stood before the crashed UFO. He could tell that it was mostly intact, but several large sections had either burned off on reentry or been blasted off into the distance once it had crashed.

With bated breath, he slowly reached a hand out and pressed it against the hull of the ship, feeling the heat from the reentry still lingering. Dipper had to swallow a squeal of joy, he hasn’t seen an alien ship before! Well, aside from the one beneath the town that is, but that one was millions of years old, this one was new. He wondered if it had been piloted, and if so, had said pilots managed to escape before it crashed? He began to pace around the ship, trying to find some semblance of a door or maybe even a hole big enough that he could crawl through inside of it that wasn’t currently engulfed in fire.

About halfway around, he heard a quiet whine that sounded almost like a dog. He turned his head this way and that, trying to find the source of the whine as he reluctantly stepped away from the alien ship. There! Half buried under a panel that had been blasted off of the ship lie something large and furry, so covered in soot and mud that he could barely make out patches of black and maybe yellow.

“Hang in there! I’ll get you out!” He doubted that it, whatever it was, spoke English. But better safe than sorry. He looked around for anyone else as he stepped forward. Not seeing anything, he turned his focus on the possible alien, looking at the panel that had it pinned. It didn’t look too heavy, but appearances could be deceiving when it came to alien tech. He carefully tapped the panel, making sure it wasn’t hot to the touch before walking around it, ducking his head to look under.

It looked like there wasn’t anything that would collapse on the creature when he disturbed the panel, so he found a good spot to lean into. He set aside his pack and flashlight before crouching under the lip, bracing his shoulder against it. Counting to three, he heaved into the panel, clenching his teeth and grunting as he gradually lifted it up, using his hands to steady it now that it was higher up. Sure enough, despite its lightweight appearance, it was definitely heavy. By the time he managed to push it over, he was panting for breath, arms trembling from the effort.

The panel hit the ground with a ringing clang, making the human wince in sympathy for the creature. He wasn’t sure if it was an alien or just a poor supernatural creature that had been unfortunate enough to be caught in the impact zone. Speaking of. He turned to inspect the creature more closely now that it wasn’t pinned to the ground. It looked like... a giant wolf maybe? It was hard to tell with all the soot and charred fur. So maybe it was just a supernatural creature after all?

He ignored the pain of regret that it probably wasn’t an alien as he picked his way over to its chest. The “wolf” practically dwarfed him, it had to be at least between 8 and 9 feet long, and it had strange horns on its head that curled and twisted around its head and towards its muzzle. It was like a mix of ram and blackbuck horns, really. He could even see that it appeared to have 8 legs that slotted neatly in between the normal four. Its sides rose and fell evenly, making him believe that it must be unconscious. He couldn’t see any signs of blood, so whatever made it whine was probably internal or maybe it had struck its head.

Worried about that, he rested a hand on its chest, feeling for its heartbeat... steady. Ok then. He grabbed his flashlight before walking around to the head, tentatively poking its muzzle with it to make sure it wouldn’t snap at him. Once he was sure it was out cold, he carefully reached up to open one of its eyes. He lifted up the eyelid to reveal an eye that was almost feline in appearance, a golden color with blue surrounding the slit pupil. He waved the flashlight over the pupil and watched it react normally, allowing him to sigh in relief.

Well... It didn’t look like it was in immediate danger at the moment, but he wasn’t an expert or anything. It should be fine for now while he searched the craft. If he was lucky, maybe there would be something or someone inside that could help him get the “wolf” back to his home because there was no way in hell he’d be able to carry it on his own. He let the eye close and gently pet the muzzle, marvelling at the softness of the fur before he could help himself.

When he realized what he was doing, he jerked his hand back, mentally scolding himself as he hurried back over to the space craft. He searched around another side and finally found an opening, the fire here had already died and the heat wasn’t intense anymore. To be safe, he spent a few minutes grabbing soil to toss around the torn hull to smother any embers that might be ready to reignite. Feeling that it was safe, he climbed inside and panned his flashlight around.

“Hello? Are there any survivors aboard? I mean you no harm.” He paused for a couple moments but received no answer. He shook his head and steeled himself for possibly gorey sights before continuing onward.

__________________________________________________________________

Dipper spent about half an hour searching the craft but found no survivors, only one corpse of some alien that might have been from an aquatic based planet considering its sort of fishy nature. Luckily it looked like its neck had been snapped so its death was probably instant. Having no way to preserve the body for research or any possible recovery by its friends, he carefully took it outside and buried it under a nearby tree. He murmured an apology to the corpse since he had no idea what kind of funeral rights its species had. Once it was buried, he returned to searching the craft to salvage what he could.

By pure luck, the only section that had been ruined completely seemed to be a containment room but he found no evidence of anything having been in it during the crash. After some experimentation with some of the tech that he’d found, he discovered one that seemed to be a device to carry large and heavy loads by emitting a beam of light under it. Pleased, he hurried back to the wolf creature and used the device on it after testing it on the panel.

With the creature in tow, he packed up the other devices, made his way out of the crash site and started heading home. The creature hadn’t stirred and its condition seemed to be the same as before so he assumed that it was probably alright.

It took some effort and he had to bypass his usual routes where he couldn’t get the creature through, but soon enough he was walking up to his cabin. With some creative thinking, he managed to squeeze the creature inside and set it down in his living room after moving around the furniture and placing down some old blankets. He could’ve put it in the garage, but he had an experiment in there and he didn’t want to risk it or the creature. Once it was settled, he got some soapy water and rags and began to carefully clean its fur, wanting to make sure that there were no serious wounds under the charred sections.

A couple hours and buckets of water later, the wolf creature was cleaned and seemed to be resting well. Dipper had found no signs of burns to its thick skin under the charred fur and no signs of lacerations or broken bones anywhere. Considering things, the creature was very lucky. Once he was sure that it was ok, he sat back onto the couch, exhausted, and admired the creature. He’d never heard or seen anything like it before. As he’d first suspected, its fur was a bright golden yellow with black patches on its paws, legs and tail as well as covering its eyes and mantling its shoulders like a scarf almost.

He didn’t feel like checking its sex just yet, but he couldn’t put it off for much longer, since he had no guarentee that it wouldn’t attack him when it woke up. Or if it was sentient like the multibear, it might consider it rude if it caught him looking. So after a couple of minutes, he reluctantly stood up and walked over to its hindquarters. Taking a breath, he leaned down to look... Uhhh... He thinks its male? He could see the telltale bulge of a sheathed dick but it also looked like it might have a vulva? He was... Just going to call him a male for now. If he was sentient, he could always correct him when he woke up.

Speaking of waking up. He looked at the time and winced. It was almost 4 am. He glanced at the creature before reluctantly heading upstairs to his room to get some sleep. Dipper didn’t want to leave the creature on its own, but he wouldn’t get any sleep at all if he tried to sleep on the couch.

________________________________________________________________

The next morning, Dipper awoke to his alarm blaring in his ear. He groaned and slapped the damn thing until he managed to turn it off. He sat up as he blinked the sleep from his eyes, grumbling about the early hour. In reality it was only 9 am, but he couldn’t let himself sleep in in case the creature woke up and tried to destroy his cabin in his panic. With that thought in mind, he lurched out of bed and stumbled into the bathroom, turning on the shower and stripping. He didn’t bother to let it get hot before climbing in, letting the chilly water help wake himself up.

After scrubbing down and rinsing off, he shut off the shower and toweled himself dry as he shuffled to his closet. He grabbed the first shirt he saw and some jeans before getting some boxers from his dresser. Once dressed, he headed downstairs, his slightly more alert mind careful to make sure that he didn’t make too much noise as he checked on his guest. The wolf seemed to still be asleep so decided to go and make some breakfast while he had the chance, glad that he’d just gone grocery shopping and had some meat that he could cook for the wolf since it was probably hungry too. (Not to mention he would be far less likely to try and eat him if there was fresh food in front of him already.)

He put the meat in the oven to warm it up and cook it a little while he made himself some omelettes with vegetables and bits of ham. He was just finishing up when he heard something moving in the living room. Quickly he placed his food off the stove and hurried into the room to watch as the wolf creature stirred. He blinked open his eyes that seemed to be out of focus before he suddenly leapt to his paws, growling and looking ready to fight as he looked around the room. Dipper froze in place, not wanting to startle him.

The creature’s gaze found him though and then he seemed to pause in surprise, his hackles lowering as pressure began to grow in Dipper’s mind. He winced as the wolf sat on his haunches, all aggression gone as quickly as it had appeared. Dipper tried to wonder about the sudden shift in attitude, but the pressure in his mind only continued to grow. Suddenly it broke, and a voice began talking in a  _ lot _ of strange languages. Most didn’t even seem possible for a human throat to replicate before it finally settled into broken English.

“ _ Who you? Where me? _ ” The wolf continued to stare Dipper in the eyes before it clicked. The creature was telepathic!

“O-oh! Um, hello there. My name is Dipper Pines. You’re in my home.”

A pause before he replied. “ _ How here? _ ”

“I was hiking in the forest last night when something crash landed nearby, when I checked it out, it was an alien ship. You were pinned under a panel near the ship and I managed to get it off of you. The only alien in the ship was dead so I buried it and found a device that let me carry you here. I cleaned you up and made sure you were ok.”

Another longer pause as he seemed to be processing his words. “ _ Save me? Thank you. No mourn alien. They take me too... _ ” He paused, probably trying to think of the word in English. “ _ You call zoo? _ ”

Dipper’s eyes widened in surprise. That explained the containment room. “So you’re an alien too? But why would they take you to a zoo if you’re sentient.”

He seemed to scoff at his reaction. “ _ What else be? Other not see my kind as sentient. Say just animal so cage us. _ ”

“Well that’s not right.” He frowns a that, clearly the... alien wolf creature was sentient. Hell they were having a conversation! What other proof do they need? “And sorry, there’s lots of creatures on Earth, where we are, that are strange and don’t fit into the natural world. Plus, you look a lot like one of the natural species of Earth, but they aren’t sentient for sure when you clearly are. Oh how rude of me, I forgot to ask you your name.”

The alien wolf nodded, accepting his words. “ _ Am called Willexian Cipherationova. Mother call me Bill. You call me Bill too. Easy on human tongue. _ ”

Seriously? The first alien he meets is named  _ Bill _ ? Granted, it was a nickname, but come on. He’s waited his whole life for a moment like this and it’s such a... normal name. He keeps that to himself though. Outwardly he just smiles and nods in return.

“It’s nice to meet you, Bill. Are you hungry? I started heating up some meat for you, just in case you were.”

Bill tilted his head in what was probably surprise, likely not expecting such generosity. “ _ Would be... grateful. Captors do not feed often, make weak so no fight back. _ ” Now that he mentioned it, he did look a little skinny.

“Seriously, what the hell. You can eat as much as you like, and later I can show you the animals that you can hunt around here. I’m assuming that’s what you normally do, if you were on your home planet that is.”

“ _ I hunt. Yes. Am grateful. Never such kindness before. You no try to keep me here? _ ” Bill looked a bit skeptical of him, but he didn’t really blame him considering he’d been treated like shit until now.

“Of course I won’t try to keep you here, you’re not my prisoner or anything. I brought you here to make sure that you were ok and figured that you’d be on your way once you were. But since you’re an alien, I have no idea how you could leave the planet. Earth isn’t exactly that advanced, humans have barely begun to explore our own solar system. To be honest, you’re the first alien that I’ve met, many humans don’t even believe that aliens exist and those who do think the government keeps you secret and imprison you in top secret bunkers.”

From the curling of his lips, he guessed Bill was frowning. “ _ So am trapped here. But no zoo. You help me hide? _ ”

“Uh, yeah sorry. I mean, there’s an alien ship buried under the town but it’s been there for millions of years and seemed to be a prison transport of some kind. I only know about it because my great uncle showed me years ago. But yeah, I can help you hide. The government doesn’t come to this area anymore so you’re safe here. Oh, let me get you your food.” He turned to walk back to the kitchen.

“ _ Is fine. I come with. _ ”

Dipper turned to tell him the kitchen was too small for him to fit in but the words died in his mouth as Bill’s form began to ripple. His extra legs were sucked back into his body and he started to shrink in size, his muzzle flattening into his face. His fur began to withdraw too, leaving a thin covering on his forearms, chest and his legs as well as his bushy tail. After a few minutes, Bill stood at about 7 ft tall on two legs that started out human-like before melting back into full canine, wolf ears flicking on top of his head amongst golden blonde hair. Without all the fur, Dipper could see that his skin was a dark brown, almost black color and he averted his eyes as he quickly reconfirmed that he was indeed male. From the brief glance that he’d gotten, his now exposed dick was strange in appearance but he couldn't really expect the alien to have a human dick even if he could pass for one with the right outfit.

“Is something wrong?” The alien's voice was strange now that it wasn’t in his head. Sort of high pitched but at the same time low, giving an echoey feel to it.

“N-no just surprised is all. I didn’t expect you to be able to shapeshift.” He kept his gaze averted towards the ceiling.

“You no like? You no look at me. Can change back if gross to you.”

“No!” He lowered his gaze to look into his eyes, vaguely noticing that they had remained the same, fighting the blush that threatened to redden his cheeks. “You’re not gross at all, it’s just for humans, my species, it is impolite to look at someone naked and it’s considered indecent for someone to walk around naked.”

Bill’s brows furrowed in confusion. “Was naked before? Why different now?”

“Cause before your... ahem. Your reproductive organs were hidden by your fur and sheath. You also looked more animal before and now you look more human. Humans are strange that way, we don’t mind if animals are naked but we do if other humans are.”

“Hmm... Me see. You have... Clothing me wear?”

“Yeah, I can probably find something. You don’t have to completely cover yourself, it’s just a bit embarrassing for me if your reproductive organs are exposed. Are you sure you want to wear something? I can always just get used to it.” He didn’t want Bill to be uncomfortable, even if it meant that he’d be a blushing mess every time he happened to look down.

But Bill nodded his assent, wanting to at least do something for his host since Dipper was being so kind to him. With the nod, Dipper hurried upstairs and looked for his biggest pair of shorts. He sent a silent thank you to whatever deities that were watching that he still had the cargo shorts that his grandmother bought him without realizing they were way too big. With shorts in hand, he rejoined Bill who had been looking around the living room and adjusting to being on two legs again.

“Here you go. You just slip your legs through these holes and then fasten this tie to keep them in place.” He handed them to Bill who looked at the shorts before awkwardly following his instructions, having to let Dipper tie the strings since he didn’t know how to. The human had to himself to ignore the delectable sight of his hips and the happy trail of hair that matched the hair on his head.

... 

Maybe he should have insisted on Bill wearing more clothes. He was way to gay for this. He pulled away once the ties were secure and smiled at Bill who smiled back. “How do they feel?”

“Strange. Not wear clothes before. My kind no need clothes.”

“Are you used to seeing males and females naked then?”

“What that?” Bill’s eyebrows quirked up questioningly.

“Huh? Males and females? The two main sexes?”

“You have two? Have one.”

Now it was Dipper’s turn to look confused. “Then how do you reproduce if you only have one sex?”

“Have all parts needed. Can be mother and father. Prefer father. Make me male. I leader of pack. Make me Alpha male.” He said that as though it was obvious while Dipper was just bewildered. He had no idea such a thing could happen with a sentient species. Sure there were some species of animal that could be both the mother and the father, but they were typically things like snails or simple sea creatures, nothing so complex as a higher species.

“Huh. With humans, most are only born with the parts to be a mother or a father, though there are some born with multiple parts, most parents have corrective surgery done to their newborns so they only have one set.”

“Why? More better for species if can be both. More pups. More chances for species.”

“That is true I suppose. As for why they do it, most do it because humans are kind of stupid and some think that it’s unnatural to have more than one. Sometimes we’re even born with the wrong set and want the correct set but other humans don’t want to let them.”

Bill snorted at that and was going to continue when Dipper’s stomach growled, making him blush. “Ah, sorry. Can we continue while we eat?” With Bill’s nod of agreement, Dipper led the way to the kitchen, pulling out Bill’s breakfast from the oven while the alien sat down at the table. Luckily the extra time they spent talking allowed for it to be cooked more thoroughly than he’d been initially planning. He served some onto a plate and grabbed his omelettes, setting them down on the table.

“Can you use utensils?” He picked up a fork to show it to Bill.

“Use with food, yes? Show and use. If be here, learn ways.”

The human nods, showing him how to stab the meat and break off a bite sized piece. “When you put it in your mouth, don’t bite down, just use your closed mouth to pull the food off the fork as you remove it from your mouth. I’ll show you later how to use other utensils, for now you should be fine with a fork.”

With a hum of acknowledgement, Bill took the fork and, with some trial and error, managed to figure out the fork and began to eat. Relieved, Dipper walked to the fridge and poured glasses of water for them both before finally sitting down so he could eat too.

Of course he had to show Bill how to drink the water too, but otherwise, they ate in companionable silence, both too hungry to really care about talking when they would have plenty of time to do so later.


	2. Chapter 2

**Notes for the Chapter:**

> Hey guess what. This is gonna be at least 2 more chapters. XD Sorry for the long delay, I had most of this written already but it got put on the back burner for the moment. Warning, there is casual talk about genitalia and reproductive methods, but also remember that this was supposed to be just pure porn that I just couldn't help but expand upon. THIS STILL IS PORN, JUST A VERY, VERY LONG ONE.

The next few days passed without much hassle. Dipper had set up his spare room for Bill and told him that he could decorate it as he liked, just to run it by him first. He then used some of the leftover fashion supplies Mabel had left behind during her last visit to figure out what size clothes his guest would need. Next he had pulled up some clothing styles on his laptop and showed them to Bill, asking what he liked. It had been a bit tough for the alien to figure it out though, since clothes were completely new to him. Once he’d picked them out, Dipper ordered them online so they didn’t have to worry about taking Bill to the mall, not even blinking when his guest had picked out some womens clothing.

There had also been some discussion about ‘pronouns’ since Dipper didn’t want to offend the alien, but Bill had been fine with being called by he/him. When he had done some research on his own time, he concluded that the closest gender identity he could compare Bill to would probably be genderfluid male presenting or non-binary male presenting. Of course that didn’t really matter, but it helped Dipper think of a way to explain it to others should they ever find out about Bill.

Once Bill had felt up to it, Dipper led him back to the wreckage. The fires had long since died and the ship was still mostly intact, but there was no chance that it would fly again to their disappointment. When Dipper had asked what had caused it to crash, the wolf had simply shook his head.

“Not know. Fly fine at first, was napping. Felt something hit ship. Lights flicker, door open so me investigate. Was in hallway when ship shake again. Knew we in atmosphere of planet. No see captor so me curl up. Bones and fur strong, protect belly. Ship hit ground, me sent flying with wall. Wall hit head. Blackout. Next know, me wake up to you.”

The human rubbed his jaw in thought. “Sounds like you were hit by something or someone and it short-circuited the ship which probably caused it to fall into a collision course. There were no signs of a struggle inside the ship, the alien, the pilot I’m guessing, had its neck snapped, but that could have been caused during the crash.” He turned to Bill. “Do you know what planet you were being taken to?”

“Planet have no name in human tongue. Outside system, but neighbor system. Taken from inner galaxy to zoo in outer arm. Make zoo popular, force pair with another, make pups, make more popular.”

Dipper grimaced and shook his head. “That’s seriously messed up. Then again, humans do the same thing, but at least we know our animals aren’t sentient.”

“How know?”

“What?” He looked at the other in confusion.

“How know, not sentient?”

“Because how humans identify sentience is the ability to form complex thought and to communicate that thought to others. Some animals come close to that, but because they can’t communicate or do things like record their thoughts, they aren’t considered sentient. You’re clearly sentient because of things like this, we’re having a conversation and even if you couldn’t speak English, the language I speak, we could still figure out a way to communicate with each other. Very few animals are capable of that and even then they’re rare cases. The only exceptions to the rule are some supernatural species but they aren’t globally acknowledged and most humans don’t even know they exist.”

Bill looked at Dipper for a few moments in silence until the human’s skin itched. Finally he nodded in acknowledgement of his words. “Humans strange. Not sure if me like. But me like you. You smart and think.”

Dipper blushed a little at that and smiled at him. “Yeah I get that, humans are a pain in the ass. And, thank you, I like you too. You’re a lot of fun to talk with.”

The wolf grinned a little, his tail wagging happily. It was really cute, if he was being honest. Then again, if he was being  _ really _ honest, he’d admit that the alien wolf was drop dead gorgeous. But Dipper knew better than to assume that he’d be interested in a plain looking human like himself. Still though, he wouldn’t mind being underneath the alien sometime. Really, the fact that Bill was basically a sentient alien wolf didn’t even bother him, which at this point in his life, he wasn’t at all surprised by.

After that exchange, the pair searched around the ship for any other supplies and scrap that they could salvage. They were using the same device Dipper had used on Bill to carry their loot, so they didn’t have to worry about weight.

The day after Bill had woken up, they had discussed what to do about the wreckage. Eventually they came to the agreement that if it wasn’t able to be repaired, they would salvage the parts to make the alien a little bunker near the cabin. This was in case Bill wanted to hide from other humans since he was hesitant to trust them, for good reason. The only reason why he wasn’t skeptical of Dipper was because the human had been nothing but accommodating for his guest and had promised Bill that he could leave at any time if he wanted to.

After a day of hard, sweaty labor, they grinned at each other as they surveyed the veritable mountain of materials they had to work with. Dipper had never been more grateful of his tutelage under his uncle as they talked about what they wanted to do for the bunker, walking side by side with hands brushing. The platform followed behind them, forcing them to take the long way much like Dipper had with Bill before. Not that either of them minded.

_________________________________________________________________

A comfortable pattern formed for them for the next week or so. They would spend every other day lugging materials and tools from the ship to the cabin and then spend the alternating days organizing the salvage. Then they spent another couple days planning for the bunker, carefully designing it so that even on the off chance the government showed up, they’d never find it. Once they had a general idea of how large they were going to make it, they began excavation. It was slow going and they spent 2 weeks on it before they had to take a break, many times having to stop for the weather. It was starting to get colder out, and Dipper was pretty sure they wouldn’t finish before winter set in which would put them at a total standstill until the ground thawed in spring. He sat down to talk it over with Bill during an early dinner one night.

“We’ll probably have to put a halt on the bunker for the next few months.” He frowned as he spoke, looking over at the calendar on the wall.

“Why?” Bill followed his gaze, wondering what the issue was with it. “Paper with numbers track days, yes? Days running out to something?” His English was getting a little better, but the human was used to the broken English by now.

“Sort of. You see, my planet’s axis was tilted billions of years ago when it was forming, this causes the planet to have varying temperatures in the northern and southern hemispheres. We have what we call seasons, where the average temperature of that part of the hemisphere is consistently hot, cold or transitional. This also gives us different types of weather for those seasons. Right now, where we are, we’re in the middle of the season called Autumn, which means we’re transitioning from hot weather to cold weather. The cold weather season is called Winter, and in this part of the hemisphere, it can be very cold and it snows heavily. When that happens, the ground will freeze so we won’t be able to dig.”

Bill nodded as he spoke, a thoughtful expression on his face. “Me see. So Earth like home. Home has seasons too.”

“Wait really? What’s your home like then? You haven’t really told me about it.”

The other sighs, frowning and looking reluctant to discuss it. Dipper was about to drop it but then Bill spoke. “Home is like... Like Earth, but bigger. Very boring though. No in... individuality. You play role you given, no other. Me was chosen to go to captors cause me no like role given. Me fight, me try to change things so me not wanted.”

“So you were given away...?” He was horrified by that, his own people gave him to aliens that didn’t even consider their race sentient just because he was trying to make things better? “That’s horrible, I’m sorry Bill.” He unconsciously reached over, resting his hand on Bill’s, failing to notice the other had stiffened a little in response.

“Is ok. Others no want better way, no deserve better way. Besides, have you now. Not so bad in end. If anything, me thank others, cause now me here. Am free.” Bill gave him an almost shy smile, bringing a faint blush to Dipper’s cheeks.

“Well... I guess if you think about it that way, I’m happy you’re here too. It gets kinda lonely out here on my own.” He admitted sheepishly, smiling back at the alien.

“Why alone anyway? No pack?”

Dipper shakes his head with a small shrug. “My twin sister is on the other side of the continent learning how to make clothes that people will spend a lot of money to wear.” Easiest way he could explain fashion. “My great uncles passed away a year or so ago, and my parents and I aren’t... aren’t on speaking terms anymore.”

The blonde alien tipped his head curiously, unintentionally being too adorable for Dipper not to explain. With a heavy sigh, he admitted to him one of the things he hated most about humans. “In human terms, I’m known as a homosexual, also known as gay. It means I’m only attracted to people the same sex as me, which is other males. My parents are among the humans who think that it’s disgusting or wrong. They wanted me to... mate with a female so I can produce offspring. While I wouldn’t mind having offspring of my own someday, I can’t be sexually aroused by or feel any romantic attraction to females, which is necessary for me to reproduce by normal means. Of course there are alternative methods, such as surrogacy, which is where you find someone with a womb who is willing to carry your offspring and then gives them to you once they’re born. Or there’s adoption, where you take in offspring of others who have usually either died or were unfit to raise their offspring, and you raise them as your own.”

When he paused and Bill said nothing, he glanced at the other and saw his brow was scrunched up which meant he was processing what Dipper had said. So he finished it off with one last bit. “Because I refused to follow their desires, they want nothing to do with me, nor I them.”

Silence stretched out between them for a few minutes as Bill mulled it over. “So... you no want position they gave you, yes? You rebel, they leave you. You like me then.” Bill’s hand flipped over, tangling their fingers together and making Dipper jump. He hadn’t even noticed that his hand was even on Bill’s in the first place, let alone had remained there this whole time. The blonde smiles softly at Dipper’s reaction, finding it cute. “We the same.”

“U-uh yeah... I guess we are.” He blushed a deeper red than before as he struggled not to squeal with delight. They were holding hands!

“You like me though, but not same sex?” Bill’s smile turned coy, something that wasn’t all too new to the brunette and made him squawk in surprise at the realization that Bill knew he was crushing on him.

“H-how did-!” His face burned a deep cherry red as his free hand covered his face, too embarrassed to look at the alien.

“Can smell. You give off breed scent when you look at me. Plus you say you like me.” He smiled smugly at the brunette’s reaction.

“D-damn it... I-I’m sorry if I offended you or grossed you out or anything...” He was still covering his face, but he couldn’t bring himself to pull their joined hands apart.

“Dipper.” Bill cooed a little, reaching over and taking the human’s other hand. “No gross to me. Like you, remember? No know human courting. Try to figure out, but folding glass device not help. No understand broken English.” Basically he tried to use the laptop to find out how to date the human way. The fact that he had made Dipper smile a little, even as he couldn’t bring himself to look the alien in the eye.

“I thought you were just saying that you liked me as a friend...”

“Eh, language hard to translate. My kind no have same terms. We mate life, courting is way to... trial run, guess say. Me thought strange, no want mate before. But you nice, clever. You help even strange me, no blink. Me give try with you, but not want push. Once mate, no leave ever. You no be with others to mate, me no leave you here.” His expression turned serious, reaffirming to Dipper that he meant what he said, that he wasn’t just exaggerating.

“Woah, woah, woah.” Hold up. He looked up at the alien in shock, eyes wide. “You like me so much in only a couple weeks that you’d be willing to mate with me, for life?”

Bill simply shrugged as though it should be obvious. “Yes, courting take few days at home. You pick partner that smell good, give few days to talk, work together, hunt together. If like, mate. If no, no mate, leave and try with someone else. Me like you smell, we work for weeks, me like still. Much longer than normal, but no know human courting. No know if say me like you and want to mate, you be angry, want me to leave. Nervous. Strange feeling.” He looked a little sheepish now, smiling shyly at Dipper as his ears flattened and his tail wagged nervously.

Dipper cleared his throat and swallowed, taking a breath as he began to explain. “Well with humans, we very rarely mate for life. For most of us, our goal is to find a mate for life, but many mates leave each other because they no longer feel the bond that we call love. Others do it to get money from someone in a higher standing and then leave once they get it. Or even one mate abuses the other or cheats on them with someone else, things like that. As for how we court, there’s no... Well there’s no time frame. Many people court, or as we call it, date for months or years, some even for decades without ever mating officially. And when it comes to sex, you don’t have to be mates to, well mate with them.”

He watched as Bill tipped his head once more, and once more, it was too freaking cute. “Me see, is why you give breed scent when we not mates?” When Dipper nodded he continued. “Would you be unhappy if you mate me?”

The human had to pause to think it over while Bill waited nervously for his answer. He thought about how well they got along even in the minimal time that they’ve known each other, how kind the alien was and how close they already were. Finally he answered. “I don’t think I would be unhappy, no. But I would like you to at least meet my twin first. She’s my best friend and supported me through everything. For humans, courting and mating is a big deal, and she’d be upset if it all happened without her knowing about it, especially since you’re an alien.”

Bill nodded, looking pretty relieved since it wasn’t a rejection as he’d feared it would be. “Why not tell her before?”

“Because she’s just started a new section of learning so I didn’t want to distract her from it. An alien is pretty big news, let alone the fact that you’re interested in mating with me for life.”

“Fair point. When you call then? She will come here?”

“Ah, well she should be having a break soon so yeah. Normally she sleeps in the spare room, but that’s yours now so she can sleep in my room. I’ll just sleep on the couch for a couple days.”

“No, sleep with me. No try mate, promise. No want you sleep on the couch. Give bad back.” He nodded firmly, as though to emphasize his point. To be fair, he wasn’t wrong. The couch was lumpy and he always woke up with a sore back or neck if he passed out on it. But, sharing a bed...?

“Bill it’s not you I’m worried about.” He snorts with laughter, smiling softly at the alien, squeezing his hands. “I’m more worried that I might get a little carried away if we kiss or something.”

“Kiss?” He tips head tipping and ears flicking, not knowing that word.

“Oh, I guess your species doesn’t kiss then? It’s ah, well it’s a way humans show affection and can help us get into the mood to mate. We press our lips together and when it gets more intimate, we open our mouths while we kiss and our tongues tangle together.”

Bill’s eyebrows rose and his tail wagged with intrigue. “Will you show how do? Sounds nice, and me show you affection human way.”

“O-oh-” Dipper’s face burned a deep red at the purely innocent intentions of the alien. He was like a puppy sometimes and it only made him like him more. Honestly, he probably would be very happy to be with Bill, but this wasn’t just something that he could decide just because he was horny and lonely. This was a literal lifetime commitment and something he wanted to consult Mabel on. She was the love expert afterall, and he trusted her opinion, especially since she was the only one he could really talk to about this. Ford and Stan had long since passed away, his friends had all but moved away from the Falls and it wasn’t like he could introduce Bill to his parents.

He realized Bill was still excitedly waiting for an answer, his tail wagging still, so he cleared his throat. He couldn’t say not to that face, especially since at the very least he could get a small taste of the alien. “S-sure I can show you how to k-kiss. Um, let me show you some examples before we actually try though, so you can get an idea of what it should look like.” Bill nodded excitedly, releasing Dipper’s hands so the human could pull out his phone.

With hands shaking a little, Dipper unlocked his phone and went to his internet browser, pulling up pictures of people kissing before turning the phone to Bill. The alien’s feline eyes zeroed in on the images, studying them intently as Dipper slowly scrolled down the list of photos. The images were a mix of lip kisses and kissing elsewhere, like the cheek, the nose, the back of the hand, etc. It seemed almost like he was memorizing every last one. After a couple minutes he asked to see the ones with tongue, wanting to know the difference.

“Ah, well that’s a little harder to show the actual tongue being involved since that’s inside the mouths, but I can show you still if you want.” With his nod, Dipper edited the search to show pictures of people making out, making a mental note to delete that from his search history later. Bill frowned a little in disappointment when he saw Dipper had been right about it being hard to see the tongues, but he could at least see that these were more intense. When he was satisfied, he nudged the phone in Dipper’s hand.

“Try kiss now?” His smile was sweet, his dichromatic eyes radiating a little mischief and curiousity as the sunset brought out the sharpness in his features that he’d never really noticed before. He was left a little in awe at how gorgeous the alien really was. How the hell he was interested in his plain self at all was beyond him.

Dipper took a deep breath, mentally shaking himself of the trance he’d been in, staring at those eyes, and smiled shyly at Bill. “Sure, we can try now. Just close your eyes, ok?”

Bill nodded eagerly with a beaming smile before he closed his eyes, waiting patiently to be told what to do next. Dipper watched his face for a moment before leaning forward slowly, eyes drifting closed. Slowly, delicately, he pressed his lips against Bill’s, ignoring how his own heart seemed to stutter when the alien leaned into him a little, returning the kiss. He forced himself not to lose himself in how soft his lips were, or how the alien smelled of musk, pine and, somehow, gunpowder. It was a strange combination, but it suited him and Dipper inhaled it deeply, not knowing if he’d get another chance to.

The kiss was a little awkward, little more than them pressing their lips together and less of a real kiss, but it wasn’t bad. After a couple moments, the human leaned back, face a deep cherry red as he opened his eyes. Bill followed suit but instead was beaming with pride.

“Kiss nice. Strange, but nice. Like scenting but less licking.” He took Dipper’s hand in his own again, twining together their fingers. The human assumed that this was a shared way their species showed affection since Bill hadn’t asked about it before doing it.

“I guess you could say that, but I’m not sure what you mean by ‘scenting’.”

“Oh! Scenting is putting scent on mates or pack mates. Show who with, who be angry if others mess with you. Way to protect and show dominance without fighting. Guess no work with humans?”

He shook his head with an apologetic smile, squeezing his hand. “No, I’m afraid not. Humans have a very weak sense of smell and we can’t really differentiate scents on someone that well. We even have ways to augment our scents so we smell nice to others, but they’re very strong and fade over time.”

“How do that? Sound like scenting a little.”

“They’re called perfumes or cologne, depending on which sex they’re meant for. They can make you smell like different flowers, spices or places in nature, or make you smell more musky. Most people can’t tell the difference between similar scents though, so it isn’t really the same thing. How we show if we have a mate in most human cultures is by having a fancy band of metal with jewels embedded in it that we wear on this finger.” He uses his free hand to tap his left ring finger.

“Why that finger specifically?” He leaned down to get a closer look at the finger, wondering if there was a special trait to it.

“Because that’s the only finger that has a vein that leads directly to the heart. It’s a symbolic way to show that our heart is bound to another. Some rings are so special to the owners that they get passed down from generation to generation. Especially if the first marriage, which is what we call the bond between mates, was one of the lucky few to be for life. It’s considered good luck to the descendants in their own marriages. Does your kind have something like that?”

“Hmm... Not ring, no. But we have venom in reproductive organs. When mate, venom changes biology in mate so can have offspring. This keep mate with mate. Other try mate, end badly.”

“Hang on, how do your reproductive organs have venom?” He’s never heard anything like that. “And what do you mean changes the biology?”

Bill frowns as he thinks about how to explain it in English, fingers of his free hand tapping his jaw while his tail flicks. “Have to show where venom is, but have no pictures. Show you with own organs, but you... embarrassed by it before.” Ok fair point, but he was still curious as hell about it and was willing to look now, especially if they might have sex. But before he could point that out, the alien continued. “When born, infertile. Produce eggs yes but no womb and no life possible.” Hold up,  _ eggs _ ?

“Stay infertile until mate. When mate, venom triggers fertile egg making and make womb, can now make life. But downside, venom is permanent and unique to mate. Always happen when mate too. If other mate with mate not own, venom try to make change but can’t. Instead now toxic, attack organs. Painful and slow death. Two way too, so both die. Is why mate for life. Not sure how react to you, but test on cells, yes? If not ok, no try mate. Not want you die or hurt. Happy just be here.”

Well. At least he didn’t tell him about that until  _ after _ they had sex, if they ever decided to go through with it. He leaned back as his mind tried to process all that he was told, sifting through it and picking out the questions that he still had. “Ok... So. I’d still like to see where the venom is, and I’ll definitely test out your venom on some of my cells. But, can you explain to me the ‘eggs’ part? And the venom ‘makes’ the womb? I’m kinda being thrown for a loop on that bit.”

“Humans not have eggs or womb?”

“No, no. Our females are born with a womb. During puberty, which is when they start to become sexually mature, they start to produce eggs that only are distributed one at a time, and if it isn’t fertilized, it will be discarded with the lining of the womb during what is called a menstrual cycle. This only happens about once a month, though it isn’t exact and some mothers have slightly different cycles. But the way you explained it for your species, it sounds like a completely different process with your eggs.”

“Me see, well. Womb technically there, but only as materials. No waste energy then.” He rested his free hand on his lower stomach. “Here, space and materials ready, but womb not made. When mate, venom activates dormant cells, make womb then. Eggs made in here.” He lowers his hand to his groin, poking at the bulge in his shorts. He still typically only wore shorts, even after the new clothes had arrived. “Eggs fertilized by mother, father lays eggs in mother womb. Eggs incubate for months, grow in size. Many eggs though. First ones hatch in womb, hungry. Eat unhatched eggs, make room and save mother energy. When ready, mother give birth to pups. Can be up to litter of 9, but usually 2 or 3.”

Dipper nodded slowly as he listened, trying to piece together what Bill’s home planet could’ve been like to lead to such an evolutionary path. He guessed it was probably something like how in tiger sharks the pups eat their siblings while in the two separate wombs in order to grow faster, leaving only the strongest two pups to be born. This prevented the addition of weak members to the reproductive gene pool and allowed the species to remain strong and healthy. But he couldn’t really rationalize how the mothers were the ones to fertilize the eggs and the fathers would lay them in the mother. That seemed like unnecessary extra steps to him.

“Ok then, but you say that the mother fertilizes the eggs? How does that work? In humans, the father fertilizes the egg inside the mother, and most of the time there’s only one offspring, but sometimes, like with me, an extra egg will be distributed. That or the one fertilized egg accidentally splits into 2 or more offspring. Then the egg or eggs grow into embryos then a fetus and finally a baby, there’s no hatching, and the mother carries them until they are developed enough to survive outside the womb. This usually takes about 9 months, but it’s not exact.”

Bill nodded as he processed the differences in their species reproductive cycles before answering his question. “Easier to show, but try to say in words. Father use... Me think you call ‘cock’? Father use cock to collect seed from Mother cock. Is first step in mate when want pups. Easier in wolf form, as you say. Father mount Mother and outer cock binds to Mother, then inner cock enters Mother for mating, when uh... climax?” He looked at him for confirmation and continued when a stunned Dipper nodded. “When climax, eggs travel down inner cock and laid in womb.”

The poor brunette had to lean back to process that for a moment, his brain oh so helpfully providing how the fact that the mother needs to fertilize the eggs first would prevent unwanted pregnancies. Thank you brain cause  _ that _ is what the most important takeaway from that was, not the fact that the alien just explained that he essentially has a dual-layered dick. He was only brought back to reality when Bill made a small inquisitive whine, worried that he had upset his human.

“I-I’m ok, sorry... Just uh... You say you have an outer and inner cock?”

“Only in wolf form. In humanoid form, only inner cock. Outer impractical for mating in humanoid form. Humans no have this?”

“No we just have... just have the one. And it’s pretty plain in comparison to your species... Woooow I feel a little inadequate now.” He laughs a bit, free hand combing through his curls, briefly exposing his birthmark but Bill only got a tiny glimpse and he decided that it’d be best to ask about it later.

“Not inadequate. Different. Would like see for comparison, me am curious about it, and me have to show mine so can show where venom. Can do in both forms too, but need to be wanting to mate to get cocks emerge.” Bill tried to reassure Dipper, but that just made Dipper blush heavily.

Flustered, he agreed and decided that that was enough for tonight. He changed the subject and Bill, thankfully, let him without a word of complaint. They finished enjoying their dinner and Dipper told Bill that he’d give Mabel a call and ask if she could come over to visit during her break. Afterwards, the human stood to clean up the dishes, but Bill asked if he could try. He was starting to get used to the human things, so he wanted to try to help out around the den, not wanting to be a burden if he was going to stay here.

Happy to have the help, he smiled and nodded, showing his alien companion how to scrape the scraps into the trash, then rinse off the dish before setting it in the bucket of hot, soapy water. Bill watched him and after he felt like he understood what to do, began to help. He commented how strange it was to him, since his kind normally eats things raw, but he liked it.

Once they were finished, Dipper shooed his alien to go and take a shower while he gave Mabel the call. Bill though, smirks and said he would, only if Dipper gave him another kiss. He mostly just wanted to see his human flustered, finding that it was cute, but he also enjoyed the ‘kissing’. Of course, Dipper blushed heavily, but he agreed, leaning up on his toes as Bill bent down to meet him, kissing him softly. It was a little better this time, now that the alien had a more general idea of what it entailed.

After it ended, Dipper gently shoved him, mumbling for him to get moving as he pulled out his phone. He heard the blonde alien snicker as he walked up the stairs and just rolled his eyes as he dialed Mabel’s number, waiting patiently for her to pick up the phone.


	3. Chapter 3

**Notes for the Chapter:**

> Yeeeeeah this dumbass ACTUALLY updated relatively soon after the last one! It's a miracle! I hope you all like this!
> 
> Warning this is where things start to get a bit SpIcY so be ready for weird alien anatomy! :D
> 
> If you have any questions, feel free to ask me anything and I'll answer them to the best of my ability!
> 
> -Lumi

To Dipper’s delight, Mabel was granted an early vacation since she was apparently way ahead of schedule thanks to her enthusiasm (and probably gallons of Mabel Juice). Instead of having to wait another 3 or 4 weeks for Thanksgiving Break, she would be arriving in a week and a half.

During their phone call, he told her a little about what was going on but kept most of it to himself for the time being. He didn’t want to worry her or anything about how he was living with a strange alien that wanted to mate him. That didn’t stop her from pestering him for details of course about the man that he’s been hinting at. He tried to get her to give it a rest, promising to tell her more once she arrived.

After a couple hours, she finally relented in her questions after he bribed her with allowing her to make her Mabel Brownies in his kitchen, which basically were brownies that were made with Mabel Juice instead of... basically every other liquid except for eggs. He would regret the decision, but so long as it got her to stop trying to squeeze more answers out of him, he didn’t care.

He said his goodbyes and then hung up, rubbing under his eyes with his free hand while he pocketed his phone. He loved his sister, but damn was she pushy for information when it came to his love life. Turning to head upstairs, he made a half-joking mental note to invent a device that would allow him to mute someone.

As he passed by Bill’s room, the door opened to reveal a (as usual) half naked alien with damp fur. “Finish talking?”

“Huh? Oh, yeah. Mabel’s gonna be here in about a week and a half since she’s been given special permission to leave early. We have plenty of time to clean up around here and get some more work done. I didn’t tell her much though, since I figured it’d be easier to explain if she met you first.” He also added in his head ‘And to save me from having her attempt to do something stupid because I have a hot alien in my home.’

“Sound good. Maybe English better when she here.” He laughs with a good natured smile, crossing his arms as he leans against the doorframe. “When want compare cocks? Can give venom sample to test. Reaction should be immediate so can wait.”

Internally, Dipper cursed. Not because he didn’t want to do it, but because his experiment in his garage still hadn’t been cleaned up. He had been so focused on what was going on with Bill that he’d yet to go back to it. “I’d like to do it as soon as possible, but I need to clean up an old experiment in my garage first so I can examine the venom properly.”

Bill hummed and leaned closer with a knowing wink. “Can show you cock still, just collect venom later. Have two forms, remember? Need plenty of time to examine each.” Now that he knew that he had a chance to mate with the human, he felt like he could be more flirtatious. Sure there was still the risk of the venom that they had to be careful of, but it had been taking all of his willpower not to come forward with his proposal. Plus, he really liked seeing Dipper blush.

And blush he did.

Dipper’s face bloomed a gorgeously deep red color that spread beneath the collar of his shirt. It made Bill want to yank off the silly fabric to see just how far down that beautiful color spread. He licked his lips, eyes narrowing a little as he stifled the part of his mind demanding for him to claim the brunette now. Dipper’s embarrassed cough brought his attention back to their conversation.

“I... umm... I guess we could do that whenever... whenever you want. I-I’d like to take a shower though so, um. Let me know when I get ou-” He starts to walk away when the alien gently grabs his wrist and yanks him against his chest, damp golden fur only hiding the upper part of his chest in an inverted triangle so Dipper could feel his developing abs. He smirks as the human’s blush manages to grow deeper.

“Hurry back~ I would like to do when you finish~” He purrs as he leans down, getting close enough that barely an inch separates their lips as he stares into his eyes. Dipper’s breath hitches in his throat at that plus the close proximity, his breeding pheromones practically smothering Bill’s nose, not that he was complaining.

Dipper manages to nod before Bill releases him, watching in amusement as the human practically flees to the bathroom, watching his plump ass jiggle as he leaves. Yeah he really hoped that the venom was compatible because he  _ seriously _ wanted to mate with him. He could only imagine all the glorious sounds that he’ll make as his cock pounds into his hole, pumping him full of his eggs, their young. He growled softly at the images, cock stirring a little in his shorts. It would be sheer torture to resist the urge to mate the human, but it was necessary if they were going to do this.

He turns back into his room to wait patiently for the human, confident that he wouldn’t be kept waiting for long. He settles down on his ‘bed’ and lounges there with a content sigh. It still amazed him how  _ cozy _ it was compared to his nests on his home planet or the pathetic platforms that he’s slept on since being captured by aliens. He had never slept so well before and he doubted that he’d ever want to give this up.

It was about 10 minutes later when his ear flicked towards the sound of his human nervously approaching his room. He opened an eye and looked at the doorway to watch as Dipper approached it, fidgeting nervously with his hands. His hair was still dripping a little and he only wore a pair of loose shorts and a t-shirt that had a picture of the human stereotype of what a UFO looked like, saying ‘I believe!’ below the beam of light coming from it. It made Bill smile as he sat up, finding the human adorable. Wordlessly, he crooked a finger at Dipper in a human gesture that he had learned meant ‘come here’.

Dipper swallowed thickly and tentatively stepped inside the room, walking over to the alien’s bed before climbing in, biting his lower lip as he looked everywhere BUT at the sexy blonde. Bill of course snickers at this and shifts so that he’s sitting comfortably across from Dipper. “No need be embarrassed. Just us. I like you. You like me. Is ok.”

That seemed to simultaneously, paradoxically really, put Dipper at ease and make him more nervous at the same time. He took a deep breath as he tried to steady himself. “I-I know, I’m just... excited? And worried? Like I really like you too, but this is all so much more complicated than I thought it would ever be? I just don’t want to accidentally go too far because we couldn’t help ourselves.”

Bill’s smile softens and he reaches down to cup his jaw, making him tilt his face up to his own. “It will be alright. I promise. Will not let anything happen that you not want. Will not break trust.” That seemed to reach through to the human since he nodded and began to relax a little. Bill leaned down to kiss him softly, wanting to help him grow more comfortable as well as help to get them both ready to mate. They may not be going through with anything, but they needed to be aroused since they were going to compare their cocks and get an idea of how it would work between them.

Dipper melted into the kiss easily, leaning into him as the blonde drew his body closer to his own. Some making out certainly wouldn’t hurt and Bill was one helluva fast learner, his tongue work leaving Dipper breathless once they opened their mouths to each other. Soon enough though, the kiss ended as the alien pulled away, the front of his shorts squirming a little and a tad bit damp.

This made the human’s breath hitch a little as Bill leaned back so he could raise his hips, pulling down his shorts and allowing a strange sight to spring up. In place of a normal cock, instead there was an almost 9 inch long tentacle-like appendage. It wasn’t quite as flexible as a tentacle, but more solid instead. It was also  _ thick _ , at least 3 inches in diameter and it was black in color with an almost golden sheen to it. At its base was a sort of bulge that looked like it could inflate, Dipper’s face flushing a deep red as he realized that it was a knot. Just beneath the knot, almost cradling it, there seemed to be some kind of golden yellow, stiff flaps that looked like there might be something thin and sharp jutting off of them.

Bill let out a soft hiss of relief as his cock squirmed free of his shorts, fangs flashing a little when he settled back down on the bed. He noticed Dipper’s intense stare and snickered quietly at the mixture of awe, hunger and curiosity that flickered across the human’s face. “You like? Can touch. Need to lift out of way to show Mother part anyway.”

The human shook himself out of his thoughts at Bill’s words and swallowed a little, locking eyes with him to make sure that he really did have permission before shyly reaching forward. The cock seemed to sense his approach and rose up to meet his hand, the head of it almost seeming to nuzzle into his palm, letting him get a closer look. In place of a normal slit and urethra, there was instead a round, indented hole that was similar to an anus. It almost... winked at him, opening and closing a tiny bit as he continued to touch and almost caress it.

Above him, Bill was swallowing back a moan and a growl at the contact. It felt good, but at the same time it wasn’t anywhere near enough. With a great deal of will, he suppressed his instincts and just let the human continue to explore. When his hands began to slide lower, closer to his knot, Bill stopped him. “Not touch further down. Venom spines beneath knot. Not hurt, but still venom.” Dammit his English was failing with the effort of keeping himself in control of his hormones.

Dipper looked up at him in surprise before leaning closer for a better look, not noticing that his cock was rubbing itself against his chest now, seeking to find a way under his shirt. Sure enough, now that he was closer, he could see that the sharp things on the flaps were extremely short, fine spines. “This is where the venom is injected from?”

He grunted softly in acknowledgment, inhaling as he steeled himself further. “Only in this form. In other, spines on inside of outer cock but less dangerous.”

“Less? How does that work?”

The alien scrunched his brow as he tried to piece together the right words in his mind before answering. “Is like... Only sharp when mating, when not, soft. Plus only ones at base release venom, others keep mate in place with no pain. Easier to show, but wrong form.”

Dipper sat up, squeaking when he finally noticed that the tip of Bill’s cock had managed to slither its way into the collar of his shirt, seeming to be prodding around for a place to insert itself. He blushes heavily as he gently removes it, much to Bill’s amusement. “S-so um. Alright then, I guess I can wait until the next time to check that out. T-then can you show me your ‘Mother’ part?”

Bill hums and nods, leaning back in his bed and spreads his legs, his tail wagging a little to the side. “Lift up cock to see, but no touch inside. Venom spines just inside.”

He nods, blushing heavily as he lifts the cock out of the way to reveal a hole beneath it. It was similar to a human’s vagina but it seemed to lack most of the extra bits, seeming to solely be the outer lips and the vaginal hole. Dipper was seriously beginning to wonder how the hell Bill peed. He leaned closer, trying to find some kind of clit, but found nothing. Did Bill’s species lack one entirely? How did they get their stimulation then?

Curiousity getting the better of him, he asked the alien directly.

“Stimulation? All stimulation is internal. Have many sensitive spot lining inside of Mother part and inside cock. Outside cock one big sensitive spot, is why stay internal when not mating. Also... Pee?”

“Yeah, pee. How do you relieve excess fluid waste?” Wait,  _ inside _ his cock? Oh yeah, he had said that the Father took the semen from the Mother via their cocks, he guess that meant that the Mother’s would go inside the Father’s.

“Ooooh. No fluid waste. All toxins go out anal tract in excrement, fluid goes into making other fluids.”

Dipper mentally jots down this information, fascinated by it as he sits up, releasing Bill’s cock and allowing the alien to sit up. He was about to ask more questions when said alien smirks and pokes him in the chest gently. “You turn to show~”

He immediately gets flustered, stammering over his words as he tries to say  _ something _ but  _ can’t _ . Bill just snickers and leans down, quieting the embarrassed human with a warm kiss that has him stiffening up before relaxing again. He let out a soft sigh as he leaned up into it, only for the alien to pull away with an expectant look. Dipper blinked before his brain recalled what he was supposed to do and he smiled sheepishly at the other man.

Taking a deep breath, he leaned back and hooked his thumbs under the hem of his shorts and took them off slowly, his own half hard cock bouncing up into the cool air of the room, making him hiss softly. He swallows and self-consciously looks away from Bill, his own 6 inch dick feeling rather pathetic and boring compared to the aliens.

But for Bill, he’s absolutely fascinated by the human’s cock, ears pricked as he was leaning closer and gently taking it into his hand, making Dipper squeak in surprise. He carefully moves it around, amazed by the simplicity of the design. He rather likes it, his own cock feeling overly complex in comparison. “... Fascinating...” His voice was soft with awe as he reached down to gently cup Dipper’s balls as he wondered at their purpose.

Caught off guard by his words and the sudden attention to the sensitive sack, he looks at Bill in shock, blushing heavily. Before he could say anything though, Bill was asking his own questions. “What is this for?” He carefully rolls the soft orbs inside of the soft pouch of skin.

“M-ngh, my balls? They’re where my sperm is produced and stored until I- ffffuck!” Bill happened to rub against a particularly sensitive spot, making Dipper’s cock grow harder. “Until I orgasm...” He managed after a couple deep breaths. “They’re very sensiiiitive and delicate, but sadly evolution decided that sperm can’t surrrrvive at our internal body temperature so they hang below so they can be coooooler.” Internally he was whining. ‘Dammit Bill stop touching me when I’m trying to explain!’

Said alien was unaware of his struggle, inspecting the thickness of Dipper’s dick in comparison to his own. “Will fit easily, that is relief. I like your cock, simple and sexy.” Dipper squirmed under his touch, embarrassed by Bill’s words but pleased as well, happy to hear that he wasn’t disappointed or anything.

After a couple more moments, Bill finally released his dick and sat up. He tips his head in thought, as though he just had a realization. “... Where put cock?”

_________________________________________________________________

After several hours of having to explain to Bill how male humans have sex with each other (dear Stars did he never have to think that he’d have to explain this to a full grown man, even if he was an alien), Dipper finally convinced said Alien to let him go to bed, promising to tell him more after he cleaned up the lab the next day. He crawled into his bed, trying to ignore how hard his dick still was because he just wanted to sleep.

This proved to be a futile effort and he grumbled to himself as he grabbed his lube from his nightstand and made sure his tissues were ready. He amusedly thought to himself how he could have used this as a demonstration for Bill when his cock throbbed in his hand.

Huh. Exhibition kink. Didn’t know he had that.

Deciding to roll with this new discovery, he shyly imagined Bill sitting across from him, watching him with those unique, gorgeous eyes of his full of curiousity and lust as Dipper removed his shorts once more, cock springing up and legs spreading to expose his puckered hole. He bit his lower lip as he poured some lube into his hand and spread it between his fingers and hands after setting aside the bottle. Slowly, he teased a finger around his hole, in his mind Bill’s eyes would be following the motions almost as though he were hypnotized.

He finally dipped a finger inside as his other hand wrapped around his cock, beginning to stroke it slowly as he carefully pushed his finger in deeper, moaning quietly and leaning his head back. He was so focused on what he was doing that he failed to notice that his bedroom door silently opened just a crack, just enough for a certain alien’s eyes to see through.

Dipper’s thoughts had unconsciously reached out to Bill, basically broadcasting to the alien that he was thinking about him as he pleasured himself and that he  _ wanted _ him to watch, so watch he did. He watched as Dipper gradually added more fingers until he pulled them out, only to roll over onto his stomach and raise his hips up in the air, giving him easier access to thrusting his fingers in and out of his ass. His hand stayed at a slow and gradual pace, keeping his main focus on pleasuring his tight hole.

He continued to watch as Dipper whined, finding the depth and width not enough so he pulled them out and shakily got to his feet, walking out of sight before returning with a sealed box. The human opened the box and pulled out a large, detached cock (oh right, he had mentioned that humans used replicas of cocks for self stimulation) and placed it on the bed before putting the box on the floor. He climbed back onto the bed and grabbed the bottle on the nightstand and poured the fluid inside on the cock before getting back into position.

Once he was laying on his chest again, he raised the cock up to his ass and slowly pushed it inside, letting out a lewd moan that had Bill biting back a growl of jealousy, his own cock twitching with its desire to be the one pleasuring the human, not the fake cock. He watched as Dipper fucked himself on the cock, the hand on his own cock speeding up until soon the human was mewling  _ Bill’s  _ name and squirming.

All too soon (for both of them), Dipper was cumming with a muffled keen, pressing his face into a pillow as his cock spurted small streams of cum onto his sheets. His body stayed in place, trembling and stiff for a minute or two before he slowly removed the fake cock, wincing as it grazed over his overstimulated nerves. Soon enough though, he was busying himself with cleaning up the mess so Bill took that as his cue to slink away back to his own room, his mind processing the display for him to use later.

_________________________________________________________________

For the next few days, things would follow a similar pattern. Dipper would spend the mornings after breakfast cleaning up his lab, throwing out the forgotten experiment and prepping his makeshift lab for the tests with Bill’s venom. During the afternoons, the human would then explain to Bill about human sex and Bill would try to explain his own species (that Dipper finally learned was called The Great Wolves, but it wasn’t a perfect translation since there was no word for wolf in Bill’s native language) methods for sex. Apparently they didn’t have much in the way of sex for pleasure, but some of the younger generations like Bill’s were more experimentative.

After they bid each other a good night, Dipper would once again end up masturbating and Bill would again watch from the door, learning what made his potential mate liked without as much of a risk of losing control of himself. A week later and a few days before Mabel’s arrival, Dipper was finally ready to test Bill’s venom. To accommodate for Bill’s massive wolf form without having to do this outside (where it was quickly getting colder and colder), Dipper had moved all of his equipment as close to the walls as possible and covered the floor with older blankets.

Dipper was prepping different kinds of samples of his own cells, some blood, skin and even his hair, making some control samples as well so he could make an easier comparison of how they should look and how they react to the venom. Then he prepared several vials with faux skin over the mouths to help simulate the spines being embedded in actual skin. Meanwhile, Bill was stripping off his shorts and setting them to the side, waiting for Dipper to finish before he shifted back to his wolf form.

Soon enough the human was ready and turned to Bill with an eager smile, his nerdiness outshining his embarrassment for once as he saw Bill’s nude form. “Are you ready?”

The wolf nodded with a smile. “I am.” He looked exceptionally proud of himself as he said that, having finally grasped the concept of the ‘I’ pronoun. He had made a lot of progress with his English after talking to Dipper so much about his own species and he was excited to converse with Mabel and practice with someone besides Dipper.

Seeing his (honestly Dipper had stopped trying to pretend that he didn’t feel possessive of the alien wolf) alien looking so pleased with himself made the human’s heart melt. “Good, then go ahead and change forms.”

Granted the ok from the human, Bill happily let his other form take control, falling to his hands as he began to grow in size, his missing four limbs emerging to join the others as his body rippled and shifted. It only took a few moments for the massive 8 legged wolf to be standing before Dipper once again, shaking himself as his fur fluffed up in relief. Compared to how he had looked before, his fur was much more healthy and he had filled out where he had been a tad bit too skinny before.

Dipper felt the mental link between them thrum before Bill’s thoughts reached him. “ _ It feels good to be back in this form. _ ” His lips wrinkled in a wolfy smile as he padded closer to his human, leaning down to nuzzle him as Dipper reached up to stroke his face with a soft smile of his own.

“It’s very handsome.” He agreed, giggling a little when Bill licked his cheek with a slightly rough tongue.

“ _ Too bad I can not kiss you like this. _ ” He bemoaned, settling for licking him some more and earning more giggles from his human.

“Mm well you can always make it up to me later.” Dipper kisses his muzzle sweetly, having gotten used to the sudden kisses and makeout sessions that the alien liked to start out of nowhere.

“ _ You know I will~ _ ” Bill winked an eye at him, nuzzling him again before pulling away. “ _ You ready? You will have to get me aroused, but I will be careful not to hurt you. _ ”

They had talked about it the night before, that Dipper would have to basically kneel under him and touch his sheath until his cock emerged. It was somewhat risky since Bill would have to stay standing the whole time in order for Dipper to have access to everything that he needed. The human shyly smiles up at him. “I’ll be just fine, just make sure to not lay down on me, you big oaf.”

Bill chuffs in laughter. “ _ I will endeavor not to. _ ”

With that, Dipper walked down his side and set up his vials and the vial rack on the floor next to where he would be kneeling before crouching down. He carefully maneuvered himself so he knelt in front of Bill’s sheath, licking his lips. In his wolf form, Bill was easily almost 6ft tall at the shoulder, which gave Dipper plenty of space to kneel under him. He reached up after a moment of hesitation and gently touched the golden furred sheath.

The wolf jolted a little at the sudden touch before relaxing once more, Bill tipping his head in an attempt to watch Dipper as he began to rub and pet the sheath. Bill licked his muzzle a little as he gradually began to grow turned on, his breathing growing a little deeper. The human leaned up and shyly started to nuzzle it as the tip of Bill’s cock began to emerge, blushing heavily and causing Bill to whine a little.

With some more teasing and rubbing, the cock was drawn out further and further, allowing Dipper to get a good look at the outer cock that he had been told about. It was the same golden color as the flaps that had been beneath the knot, three seams running along the sides and meeting at the tip of the cock, the whole length glistening with moisture. Once the full length of the cock had emerged, the tip of the cock split open into three flaps like flower petals, revealing the inner cock that he had seen before.

Unlike in Bill’s human form though, the inner cock was just over a foot in length and at least  _ 4 _ inches thick, the knot was hidden by the outer cock but he could be sure that it was larger too. As he inspected the dual layers of the cock, he noticed what Bill had been talking about with the spine. Lining the inside of the outer layer were countless hooked spines that almost reminded him of the barbs on a cat’s tongue. Bill had explained to Dipper that these spines were soft outside of actual mating, but once intercourse started, they hooked into the fur or skin of the Mother and if anyone tried to remove them before they released on their own after mating, they could take off chunks of whatever they were attached to.

This had made Dipper nervous but Bill reassured him that they caused no pain unless someone tried to remove them from the outside and Bill would have to actively be aware that someone was attempting to interrupt the mating. Dipper gently touched the outside of one of the flaps, guiding it to open further so he could see the venomous spines near the base of the cock. Bill let out a soft his, his inner cock seeking out Dipper in an attempt to find the potential mate that had summoned it.

Dipper smiles softly at that but ignores it for the time being as he reaches for the first vial, letting it rub against his chest as he sets about the risky task of collecting the venom. He carefully opens the ‘petal’ (as he began to call them) further and gently stuck the vial over some of the spines. The spines, having sensed that they had pierced “skin”, began to excrete a neon blue fluid into the vial. He let it fill until a certain point before removing the vial and professionally replaced it with an empty one. He repeated this process until he had several vials full of the almost glowing venom, pulling away and looking quite pleased with himself. “All done!”

Bill let out a shuddering sigh of relief, having been gradually tensing up this whole time as he resisted the urge to mate the human beneath him. He felt Dipper climb out from underneath him and he collapsed once he was sure that he wouldn’t lay on anything important, whining a little as he cock rubbed against the blankets beneath him. Dipper was busy cleaning up and prepping the vials of venom. Bill perked up a little as he managed to adjust himself, wanting a better look at his venom. He had never seen what it looked like so he found it fascinating that it was such a pretty blue color.

Dipper turned to him and smiled softly, apologetic. “I’m sorry that you’re being teased so much with no relief, Bill.

The alien shook his head a little. “ _ It is ok, it will be worth it, I know. _ ”

He couldn’t help but agree, feeling good about how the results will end up.

_________________________________________________________________

An hour later, Dipper got a call from his sister while he was in the middle of setting up the tests. He didn’t notice it since he was so focused on what he was doing and Bill was napping behind him on the blankets. It wasn’t until a couple hours later that he finally did notice, having finished his tasks and was now waiting for the results. He blinked in surprise when he saw the voicemail and played it on speaker while he packed away the extra supplies and stored the excess vials of venom.

“Heeeeeey Sir Dippin’ Dots! Guess what! I got out even earlier than expected! Turns out my latest batch of Mabel Juice led me to binge manufacturing the rest of my outfits for class! Now that they’re turned in, this Alpha Twin is a free bitch! Woo!”

He chuckles softly at her words until she says something that caught him off guard. “So since I’m free, I hope you don’t mind but I decided to come out early! I’m getting on my flight early tomorrow morning so I’ll be at the Redmond Airport at about-” She cuts off as she checks. “9 am tomorrow! I can’t wait to see you! Bye Bro Bro! Love ya!” With that the voicemail ended as Dipper’s mind went blank.

Oh shit.

**Author's Note:**

> Please let me know what you think! And I am also going to start taking requests for oneshots, so if you have an idea or want a specific kink written for, let me know and I may just write it for you! (I reserve the right to say no to some kinks/requests, of course.)
> 
> -Lumi


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